Method of treating cellulose pulp to remove odors therefrom



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F BERLIN, NEW 1:;

Ho Drawing.

To all whom it may concern:

Be it known that I, Gnome A. Brown, a citizen of the United States, residing at Berlin in the county of Coos and State of New liampshire, have invented new and useful Improvements in Methods of Trouting Cellulose Pulp to Remove Odors Therefrom, of which the following is a specification.

The object of the present invention is to remove from sulphate pulp so-called those substances or compounds whlch cause a disagreeable odor it is now known that an absorbent paper towel may be made from sulphate pulp, 1: e. pulp produced by that process of dlgestion in which the cooking liquor is rich in sodium sulphide. Such towels have the advantage that they are strong, tough and absorbent, and do not easily disintegrate when wet and leave fuzz on the users skin. One of the reatest objections to the use of such Kraft towels, however, is that, due to the process of digestion, the paper contains certain malodorous compounds, which are not removed during the usual step of washing the newl formed pulp, and which, when the towe s become Wet in use, produce a marked and disagreeable odor.

I have found that it is possible to remove such malodorous substances by the use of an oxidizin or bleaching a out without decreasin t e strength or 0t or desirable characteristics of such towels. For this purpose, I may employ calcium hypochlorite (Ca(OGl) or its uivalent, such as ordlnarily employed in b caching sulphite pulp, but in such small proportions as to accomplish the desired purpose without causing all) an appreciable bleaching action.

referably the pulp, prior to its formation into a web or sheet, is subjected to the action of the oxidant, as for example when it is in the boaters in which the pulp is sub'ected to, a. greater or lesser degree of hy ration.

For example, the washed sulphate pulp is delivered to the boaters with suflicient water to ensure proper circulation of the stock. Then bleach liquor is added to amount to 2% to of bleach based on dry pulp. That is, for 100 pounds of GEORGE A. RICHTER, OF BERLIN, NEW HAMPSHIRE, ASSIGNDR T0 BRO-r! 1.: TING CELLULOSE PULL? TO REMOVE 013038 TH R0- Application filed November 28, 1921. fierial No. 518,440.

dry pulp is added about 2 to 10 pounds of 35% bleach powder. The roll, lifted from the bed plate, is operated from 30 to minutes to efiect the thorough mixture of the beater contents and permit the necessary chemical reactions to occur, after which the roll is lowered and the stock beaten to the desired slowness or degree of hydration. This process, however, may be varied by omitting the preliminary mixing and circulatlon of the stock and starting the beatmg operation immediately after the additlon of the oxidant. Ordinarily the beatmg operation for the production of towel stock takes from 3 to 6 hours, depending on conditions. in general, it prefer to use 2 pounds of bleach powder for each 100 pounds of pulp, as the calcium compound resulting from the reaction is calcium chloride, which being highly soluble is not retained by the paper formed on the usual ourdrlnier mac ine. When a greater percentage of calcium hypochlorite is employe ,say upwards of 10% bleach powder for each hundred pounds of pulp,I prefer to first mix the oxidant with the stock by operating the roll out of contact with the bed plate, and to employ in connection with the beater an ordinary rotary washer to remove the reaction products, prior to the actual beating and hydration of the stock.

The oxidant-reacts with the mercaptans or higher sulphides and the sulphur-lignin compounds not removed by the usual washing to which the liberated cellulose fibers are subjected, and frees the pulp from objectionable odors, but does not bleach the pulp, since the color is not changed,and does not decrease its strength or impair its other desirable qualities, such for example as its absorbing properties What I claim is:

1. A process of removing malodors from sulphate pulp which comprises treating such pulp with an oxidizing agent sufiicient to react with the malodorous com ounds therein contained without materia ly changing the color of the pulp.

2. A process of removing malodors from sulphate pulp which comprises treatin such pulp wit an alkaline hypochlorite, herer ousse by oxidizing the molodorous compounds chlorite powder to 100 pounds of pulp,

contained in such pulp Without cfiecting on thereby oxidizing the molodorous comuppreciolole bleaching action on the pulp. pounds contained in such pulp, 10 3. A process of removing melodors from In testimony whereof I have uflixed my 6: sulphate pulp which comprises treating such signature.

pulp with 0816111111 hypochlorite in the pro portion of about 2 to 10 pounds of hypo- GEGRGE A. RICHTER. 

